1. Field of the Invention
The present invention relates to a lightweight adjustable trailer hitch device for towing by a vehicle.
2. Description of Prior Art
The patent literature includes many different types of trailer hitches, each made to meet one or more requirements of trailer hitches. One such requirement is the desirability of maintaining the towed vehicle in a horizontal or level position, irrespective of the height of the particular towing hitch to which it is connected. Not only is the load more evenly distributed in a level trailer, but the performance of the trailer as a road vehicle is thereby enhanced, since the suspension is generally designed for maximum performance at a horizontal attitude.
Adjustable height trailer hitches have been provided in the related art which will be discussed in the order of their perceived relevance to the present invention.
United Kingdom Patent Document No. 2,040,847 A published Sep. 3, 1980, for Reginald J. Broomer et al. describes as a third embodiment a height adjustable towbar which provides a link of the towbar lockable in adjusted positions by pivoting from an upper lug at both ends from brackets having five aligned holes along its lower edges to match with another lug on the lower end of the link ends. The differences in structure are pronounced in that a link with lugs between flanges is diametrically opposed to a yoked link accepting a single perforated flange.
German Patent Document No. 442,999 issued Jun. 10, 1926, to George Seitz describes a ratcheting hitch with a central member (with circular geared teeth at each end) that may assume various angles with respect to the connective members (with circular geared teeth ends and locking means) that engage the tow vehicle and the trailer. The weakness of this type of hitch is clear.
U.S. Pat. No. 1,914,963 issued on Jun. 20, 1933, to William T. Stephens describes a hitch for a tractor having a block with a pair of circular ears with apertures around the edges held by a trailer frame. An apertured disc matching the apertures with the circular ears has an apertured tongue. The tractor drawbar has a clevis with an apertured projection to connect with the apertured tongue of the disc. Two diametrically opposed pins are inserted through appropriate apertures of the disc and ears to adjust the height. The link in the present invention has only two apertures to connect the vehicle and trailer.
U.S. Pat. No. 1,181,877 issued on May 2, 1916, to Bennie P. Hanson describes an elementary means of adjusting the height of the light trailer by providing a question mark-shaped link with the hook portion facing upwards. There are a series of openings at each end of the link to hook up with the clevis of the vehicle and with the parallel ears of the tender's end members and the long bolt traversing the end members. This weak structure is unsuitable for present day needs for heavy trailers.
U.S. Pat. No. 5,358,269 issued on Oct. 25, 1994, to Walter L. Jakeman et al. describes a trailer hitch structure which provides for coupling a ball hitch of a trailer to a truck mount (step in bumper) with an inverted L-shaped and channeled carrier which confines an apertured similar L-shaped support member for the trailer's ball connector. The support member is thus adjustable in height. The structure is totally dissimilar from the present invention.
U.S. Pat. No. 4,248,451 issued on Feb. 3, 1981, to Roger Usinger describes a hitch assembly with a similar configuration with two L-shaped members with the second component sliding up or down the first component which is attached to the vehicle. The reference is distinguished by the clear difference in structure.
U.S. Pat. No. 5,354,087 issued on Oct. 11, 1994, to Harold W. Head describes an adjustable trailer hitch includes a stationary plate attached to the vehicle and a sliding plate with a tongue and coupler assembly attached to the trailer as the means of providing adjustment in height. The configuration is clearly distinct from the present invention.
U.S. Pat. No. 5,413,366 issued on May 9, 1995, to Eldon L. Gibbons describes a vertically adjustable trailer hitch which includes a fixed guide portion with reinforcement struts adapted for securement to a trailer hitch tongue and a vertically slidable component mounted for vertical adjustment thereon by a pair of latch pins. The hitch of this reference is distinguished by its slidable component structure.
U.S. Pat. No. 4,391,562 issued on Jul. 5, 1983, to Randall H. Hetzner describes an adjustable trailer drawbar wherein vertical adjustment of the rear end (under the trailer) of the elongated box-like drawbar on a channel-shaped and apertured anchor member effects vertical adjustment of its forward end by the use of a fulcrum under the front edge of the trailer to compensate for varying height trailer hitches on different vehicles and to enable the trailer bed to occupy a substantially horizontal position. This reference is distinguished by its different structure.
U.S. Pat. No. 3,843,163 issued on Oct. 22, 1974, to William B. Hale describes a Y-shaped trailer frame connected to a Y-shaped auxiliary frame having a threaded rod passing through the bottom leg and joined to an arm of a U-bolt around the leg of the trailer frame. This configuration is distinctive and offers no common structure with the present invention.
None of the above patents disclose a height adjustable trailer hitch assembly device for a vehicle towing device wherein the hitch comprises a vertical hinge joint block element which attaches to the trailer, a vertical hinge joint block element which is attached to the towing vehicle's bumper, and a horizontal block element for connecting said block elements. The hitch allows a trailer to remain level while capable of being attached to vehicles with bumpers of various heights, as defined by the claims.
None of the above inventions and patents, taken either singularly or in combination, is seen to describe the instant invention as claimed.